Assessing Contemporary Modularization Techniques for Middleware Specialization

1. Assessing Contemporary Modularization Techniques forMiddleware Specialization Akshay Dabholkar & Aniruddha Gokhale aky@dre.vanderbilt.edu OOPSLA ACoM 2008 Workshop Oct 19, 2008

2. Motivation: Intelligent Transportation Systems • Dynamic and constantly evolving systems • Rich in communication and information exchange • Stringent QoS and performance requirements • Invariably require middleware solutions and optimizations High Performance High Performance Adaptive to weather Differentiated Services Differentiated Services Intelligent Transportation Systems: An example DRE system Real time (customization) Real time • Gives rise to disparate middleware specialization needs i.e.,minimizing footprint, maximizing throughput, real-time computation, dynamic adaptation to unpredictable runtime changes Resource Constrained

3. Challenges in Middleware Specialization What? How? When? COMPUTATIONALREFLECTION Layered Middleware Goal is to enable specializations at all stages of development life cycle in an integrated manner. • Dynamic middleware-based systems require context specific optimizations and adaptationsi.e., middleware specialization • How can we identify these specializations?

4. Challenge 1: When to specialize? • Pre-postulated • Customizable • compile/link time, after development time • Generates specialized versions • e.g. static aspect weaving, compiler flags, precompiler directives, • Configurable • deployment/startup time, after compile time • e.g. CORBA PI, command-line parameters, ORB configuration files • Just-in-time (JIT) • Tunable • Fixed middleware core • After the startup time but before run time – init / bootstrap time • e.g. Component Configurator & Virtual Component patterns, two-step process (compile time: AOP, run time: Reflection) • Mutable • Most powerful (adaptive) • No concept of fixed middleware core so can evolve into something completely different or unexpected • e.g. MetaSockets, Reflection, Late Composition, dynamic aspect weaving

5. Challenge 2: What to specialize? • Context: Resource constrained embedded software require footprint management • Solution:Map application features to the supporting middleware features and optimize the middleware • Feature Pruning • Traditional middleware provides a broad range of features (generic) for multiple application domains • Remove unessential features • Benefits: reduces footprint, improves performance Need for consistent and correct feature management • Feature Augmentation • Traditional middleware may not provide the desired supporting features • Add the required features • Commonly used by next generation middleware designed to overcome the limitations of monolithic architectures • Particularly useful to incorporate domain-specific semantics within middleware

6. Challenge 3: How to specialize? • Model-Driven Engineering • Ability to introspect, reason about and adapt own behavior without exposing implementation • Integrates MDSD with QoS-enabled component middleware • AOP for Middleware Specialization • Factorization and separation of cross-cutting concerns from the middleware core • Generate customized versions of middleware for application-specific domains • e.g. CORBA Interceptors, Two-step process (compile time: AOP, run time: Reflection) Computational Reflection

7. Taxonomy of Middleware Specialization Techniques • Overlapping dimensions share concepts e.g. MDE/AOP includes both feature pruning & augmentation and can be used for customization as well as tuning • Dimensions can be combined to produce new variants of specialization • Serves as a guideline for synthesis of tools for design, V&V, analysis of specializations When? How? What? • Three dimensional Taxonomy • of • Middleware Specializations

8. Assessmentofthe Taxonomy

9. Open Middleware Specialization Research Areas →Pattern Languages of Specializations? → Safe specializations? → V&V of specializations? → Integrated specializations? An Integrated Tool Suite based on specialization pattern languages to support synthesis, verification and validation of specializations • Based on the survey at least four research areas show up: • Specialization of Domain-specific middleware services • Mutable middleware specialization is powerful but a dangerous technique • Application inconsistency caused by overlapping specialization techniques (similar to feature interaction problem in pattern recognition) • No single specialization that can adapt a entire distributed application

10. Thank You! Questions?